Formation of N-O-H bearing species in HNO 3 and H 2 O icy samples by heavy-ion irradiation: an infrared spectroscopic study

International audienceThis article investigates the radiolysis of a mixture of nitric acid with water (HNO3:H2O) at 16 K in high-vacuum (residual pressure < 10-6 mbar). A nitric acid-water ice film was exposed to 40 MeV 58 Ni 11+ ion beam in a heavy ion accelerator facility in France. For this astrochemically-and atmospherically-relevant ice mixture of nitric acid and water, we analyze the possible formation and destruction processes of NO bearing species, thus providing spectroscopic data in the infrared region for theoretical, laboratory and observational future studies. The irradiation synthetized eighteen species which were posteriorly examined by infrared spectroscopy: N2O, NH3, NO, NO2 and HxNyOz molecules, such as hidroxylamine (NH2OH), nitrous acid (HONO) as well as other species with bonding NO , N-H and H-ON converting surface-adsorbed nitrogen oxides into astrochemically active NOx. The interaction of HNO3 and H2O originates H-NO molecular complexes, which were investigated as particular cases of the hydrogen-bonded species formed by a more electronegative atom (N or O) interacts intra or intermolecularly with a donor atom (N or O) and observed in the interstellar medium with higher quantities or great abundances. The HNO3 and H2O destruction cross sections have been determined to be 8.5 x 10-13 and 1.2 x 10-13 cm 2 , respectively, for the mentioned experimental conditions